/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.badlogic.gdx.utils;

import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.CharBuffer;
import java.nio.DoubleBuffer;
import java.nio.FloatBuffer;
import java.nio.IntBuffer;
import java.nio.LongBuffer;
import java.nio.ShortBuffer;

/**
 * Class with static helper methods to increase the speed of array/direct buffer and direct buffer/direct buffer transfers
 *
 * @author mzechner
 */
public class BufferUtils {

    static Array<ByteBuffer> unsafeBuffers = new Array<ByteBuffer>();
    static int allocatedUnsafe = 0;

    static {
        System.loadLibrary("gdx");
    }

    /**
     * Copies numFloats floats from src starting at offset to dst. Dst is assumed to be a direct {@link Buffer}. The method will
     * crash if that is not the case. The position and limit of the buffer are ignored, the copy is placed at position 0 in the
     * buffer. After the copying process the position of the buffer is set to 0 and its limit is set to numFloats * 4 if it is a
     * ByteBuffer and numFloats if it is a FloatBuffer. In case the Buffer is neither a ByteBuffer nor a FloatBuffer the limit is
     * not set. This is an expert method, use at your own risk.
     *
     * @param src       the source array
     * @param dst       the destination buffer, has to be a direct Buffer
     * @param numFloats the number of floats to copy
     * @param offset    the offset in src to start copying from
     */
    public static void copy(float[] src, Buffer dst, int numFloats, int offset) {
        copyJni(src, dst, numFloats, offset);
//		dst.position(0);
//
//		if (dst instanceof ByteBuffer)
//			dst.limit(numFloats << 2);
//		else if (dst instanceof FloatBuffer) dst.limit(numFloats);
    }

    /**
     * Copies the contents of src to dst, starting from src[srcOffset], copying numElements elements. The {@link Buffer} instance's
     * {@link Buffer#position()} is used to define the offset into the Buffer itself. The position will stay the same, the limit
     * will be set to position + numElements. <b>The Buffer must be a direct Buffer with native byte order. No error checking is
     * performed</b>.
     *
     * @param src         the source array.
     * @param srcOffset   the offset into the source array.
     * @param dst         the destination Buffer, its position is used as an offset.
     * @param numElements the number of elements to copy.
     */
    public static void copy(byte[] src, int srcOffset, Buffer dst, int numElements) {
        copyJni(src, srcOffset, dst, positionInBytes(dst), numElements);
//		dst.limit(dst.position() + bytesToElements(dst, numElements));
    }

    /**
     * Copies the contents of src to dst, starting from src[srcOffset], copying numElements elements. The {@link Buffer} instance's
     * {@link Buffer#position()} is used to define the offset into the Buffer itself. The position will stay the same, the limit
     * will be set to position + numElements. <b>The Buffer must be a direct Buffer with native byte order. No error checking is
     * performed</b>.
     *
     * @param src         the source array.
     * @param srcOffset   the offset into the source array.
     * @param dst         the destination Buffer, its position is used as an offset.
     * @param numElements the number of elements to copy.
     */
    public static void copy(short[] src, int srcOffset, Buffer dst, int numElements) {
        copyJni(src, srcOffset << 1, dst, positionInBytes(dst), numElements << 1);
//		dst.limit(dst.position() + bytesToElements(dst, numElements << 1));
    }

    /**
     * Copies the contents of src to dst, starting from src[srcOffset], copying numElements elements. The {@link Buffer} instance's
     * {@link Buffer#position()} is used to define the offset into the Buffer itself. The position will stay the same, the limit
     * will be set to position + numElements. <b>The Buffer must be a direct Buffer with native byte order. No error checking is
     * performed</b>.
     *
     * @param src         the source array.
     * @param srcOffset   the offset into the source array.
     * @param dst         the destination Buffer, its position is used as an offset.
     * @param numElements the number of elements to copy.
     */
    public static void copy(char[] src, int srcOffset, Buffer dst, int numElements) {
        copyJni(src, srcOffset << 1, dst, positionInBytes(dst), numElements << 1);
//		dst.limit(dst.position() + bytesToElements(dst, numElements << 1));
    }

    /**
     * Copies the contents of src to dst, starting from src[srcOffset], copying numElements elements. The {@link Buffer} instance's
     * {@link Buffer#position()} is used to define the offset into the Buffer itself. The position will stay the same, the limit
     * will be set to position + numElements. <b>The Buffer must be a direct Buffer with native byte order. No error checking is
     * performed</b>.
     *
     * @param src         the source array.
     * @param srcOffset   the offset into the source array.
     * @param dst         the destination Buffer, its position is used as an offset.
     * @param numElements the number of elements to copy.
     */
    public static void copy(int[] src, int srcOffset, Buffer dst, int numElements) {
        copyJni(src, srcOffset << 2, dst, positionInBytes(dst), numElements << 2);
//		dst.limit(dst.position() + bytesToElements(dst, numElements << 2));
    }

    /**
     * Copies the contents of src to dst, starting from src[srcOffset], copying numElements elements. The {@link Buffer} instance's
     * {@link Buffer#position()} is used to define the offset into the Buffer itself. The position will stay the same, the limit
     * will be set to position + numElements. <b>The Buffer must be a direct Buffer with native byte order. No error checking is
     * performed</b>.
     *
     * @param src         the source array.
     * @param srcOffset   the offset into the source array.
     * @param dst         the destination Buffer, its position is used as an offset.
     * @param numElements the number of elements to copy.
     */
    public static void copy(long[] src, int srcOffset, Buffer dst, int numElements) {
        copyJni(src, srcOffset << 3, dst, positionInBytes(dst), numElements << 3);
//		dst.limit(dst.position() + bytesToElements(dst, numElements << 3));
    }

    /**
     * Copies the contents of src to dst, starting from src[srcOffset], copying numElements elements. The {@link Buffer} instance's
     * {@link Buffer#position()} is used to define the offset into the Buffer itself. The position will stay the same, the limit
     * will be set to position + numElements. <b>The Buffer must be a direct Buffer with native byte order. No error checking is
     * performed</b>.
     *
     * @param src         the source array.
     * @param srcOffset   the offset into the source array.
     * @param dst         the destination Buffer, its position is used as an offset.
     * @param numElements the number of elements to copy.
     */
    public static void copy(float[] src, int srcOffset, Buffer dst, int numElements) {
        copyJni(src, srcOffset << 2, dst, positionInBytes(dst), numElements << 2);
//		dst.limit(dst.position() + bytesToElements(dst, numElements << 2));
    }

    /**
     * Copies the contents of src to dst, starting from src[srcOffset], copying numElements elements. The {@link Buffer} instance's
     * {@link Buffer#position()} is used to define the offset into the Buffer itself. The position will stay the same, the limit
     * will be set to position + numElements. <b>The Buffer must be a direct Buffer with native byte order. No error checking is
     * performed</b>.
     *
     * @param src         the source array.
     * @param srcOffset   the offset into the source array.
     * @param dst         the destination Buffer, its position is used as an offset.
     * @param numElements the number of elements to copy.
     */
    public static void copy(double[] src, int srcOffset, Buffer dst, int numElements) {
        copyJni(src, srcOffset << 3, dst, positionInBytes(dst), numElements << 3);
//		dst.limit(dst.position() + bytesToElements(dst, numElements << 3));
    }

    /**
     * Copies the contents of src to dst, starting from the current position of src, copying numElements elements (using the data
     * type of src, no matter the datatype of dst). The dst {@link Buffer#position()} is used as the writing offset. The position
     * of both Buffers will stay the same. The limit of the src Buffer will stay the same. The limit of the dst Buffer will be set
     * to dst.position() + numElements, where numElements are translated to the number of elements appropriate for the dst Buffer
     * data type. <b>The Buffers must be direct Buffers with native byte order. No error checking is performed</b>.
     *
     * @param src         the source Buffer.
     * @param dst         the destination Buffer.
     * @param numElements the number of elements to copy.
     */
    public static void copy(Buffer src, Buffer dst, int numElements) {
        int numBytes = elementsToBytes(src, numElements);
        copyJni(src, positionInBytes(src), dst, positionInBytes(dst), numBytes);
//		dst.limit(dst.position() + bytesToElements(dst, numBytes));
    }

    private static int positionInBytes(Buffer dst) {
        if (dst instanceof ByteBuffer)
            return dst.position();
        else if (dst instanceof ShortBuffer)
            return dst.position() << 1;
        else if (dst instanceof CharBuffer)
            return dst.position() << 1;
        else if (dst instanceof IntBuffer)
            return dst.position() << 2;
        else if (dst instanceof LongBuffer)
            return dst.position() << 3;
        else if (dst instanceof FloatBuffer)
            return dst.position() << 2;
        else if (dst instanceof DoubleBuffer)
            return dst.position() << 3;
        else
            throw new GdxRuntimeException("Can't copy to a " + dst.getClass().getName() + " instance");
    }

    private static int bytesToElements(Buffer dst, int bytes) {
        if (dst instanceof ByteBuffer)
            return bytes;
        else if (dst instanceof ShortBuffer)
            return bytes >>> 1;
        else if (dst instanceof CharBuffer)
            return bytes >>> 1;
        else if (dst instanceof IntBuffer)
            return bytes >>> 2;
        else if (dst instanceof LongBuffer)
            return bytes >>> 3;
        else if (dst instanceof FloatBuffer)
            return bytes >>> 2;
        else if (dst instanceof DoubleBuffer)
            return bytes >>> 3;
        else
            throw new GdxRuntimeException("Can't copy to a " + dst.getClass().getName() + " instance");
    }

    private static int elementsToBytes(Buffer dst, int elements) {
        if (dst instanceof ByteBuffer)
            return elements;
        else if (dst instanceof ShortBuffer)
            return elements << 1;
        else if (dst instanceof CharBuffer)
            return elements << 1;
        else if (dst instanceof IntBuffer)
            return elements << 2;
        else if (dst instanceof LongBuffer)
            return elements << 3;
        else if (dst instanceof FloatBuffer)
            return elements << 2;
        else if (dst instanceof DoubleBuffer)
            return elements << 3;
        else
            throw new GdxRuntimeException("Can't copy to a " + dst.getClass().getName() + " instance");
    }

    public static FloatBuffer newFloatBuffer(int numFloats) {
        ByteBuffer buffer = ByteBuffer.allocateDirect(numFloats * 4);
        buffer.order(ByteOrder.nativeOrder());
        return buffer.asFloatBuffer();
    }

    public static DoubleBuffer newDoubleBuffer(int numDoubles) {
        ByteBuffer buffer = ByteBuffer.allocateDirect(numDoubles * 8);
        buffer.order(ByteOrder.nativeOrder());
        return buffer.asDoubleBuffer();
    }

    public static ByteBuffer newByteBuffer(int numBytes) {
        ByteBuffer buffer = ByteBuffer.allocateDirect(numBytes);
        buffer.order(ByteOrder.nativeOrder());
        return buffer;
    }

    public static ShortBuffer newShortBuffer(int numShorts) {
        ByteBuffer buffer = ByteBuffer.allocateDirect(numShorts * 2);
        buffer.order(ByteOrder.nativeOrder());
        return buffer.asShortBuffer();
    }

    public static CharBuffer newCharBuffer(int numChars) {
        ByteBuffer buffer = ByteBuffer.allocateDirect(numChars * 2);
        buffer.order(ByteOrder.nativeOrder());
        return buffer.asCharBuffer();
    }

    public static IntBuffer newIntBuffer(int numInts) {
        ByteBuffer buffer = ByteBuffer.allocateDirect(numInts * 4);
        buffer.order(ByteOrder.nativeOrder());
        return buffer.asIntBuffer();
    }

    public static LongBuffer newLongBuffer(int numLongs) {
        ByteBuffer buffer = ByteBuffer.allocateDirect(numLongs * 8);
        buffer.order(ByteOrder.nativeOrder());
        return buffer.asLongBuffer();
    }
	
	/*JNI 
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	*/

    public static void disposeUnsafeByteBuffer(ByteBuffer buffer) {
        int size = 0;
        synchronized (unsafeBuffers) {
            if (!unsafeBuffers.removeValue(buffer, true))
                throw new IllegalArgumentException("buffer not allocated with newUnsafeByteBuffer or already disposed");
        }
        allocatedUnsafe -= size;
        freeMemory(buffer);
    }

    /**
     * Allocates a new direct ByteBuffer from native heap memory using the native byte order. Needs to be disposed with
     * {@link #freeMemory(ByteBuffer)}.
     *
     * @param numBytes
     */
    public static ByteBuffer newUnsafeByteBuffer(int numBytes) {
        ByteBuffer buffer = newDisposableByteBuffer(numBytes);
        buffer.order(ByteOrder.nativeOrder());
        allocatedUnsafe += numBytes;
        synchronized (unsafeBuffers) {
            unsafeBuffers.add(buffer);
        }
        return buffer;
    }

    /**
     * @return the number of bytes allocated with {@link #newUnsafeByteBuffer(int)}
     */
    public static int getAllocatedBytesUnsafe() {
        return allocatedUnsafe;
    }

    /**
     * Frees the memory allocated for the ByteBuffer. DO NOT USE THIS ON BYTEBUFFERS ALLOCATEd VIA METHODS IN THIS CLASS OR
     * ByteBuffer.allocateDirect()! IT WILL EXPLODE!
     */
    private static native void freeMemory(ByteBuffer buffer); /*
		free(buffer);
	 */

    private static native ByteBuffer newDisposableByteBuffer(int numBytes); /*
		char* ptr = (char*)malloc(numBytes);
		return env->NewDirectByteBuffer(ptr, numBytes);
	*/

    /**
     * Writes the specified number of zeros to the buffer. This is generally faster than reallocating a new buffer.
     */
    public static native void clear(ByteBuffer buffer, int numBytes); /*
		memset(buffer, 0, numBytes);
	*/

    private native static void copyJni(float[] src, Buffer dst, int numFloats, int offset); /*
		memcpy(dst, src + offset, numFloats << 2 );
	*/

    private native static void copyJni(byte[] src, int srcOffset, Buffer dst, int dstOffset, int numBytes); /*
		memcpy(dst + dstOffset, src + srcOffset, numBytes);
	*/

    private native static void copyJni(char[] src, int srcOffset, Buffer dst, int dstOffset, int numBytes); /*
		memcpy(dst + dstOffset, src + srcOffset, numBytes);
	*/

    private native static void copyJni(short[] src, int srcOffset, Buffer dst, int dstOffset, int numBytes); /*
		memcpy(dst + dstOffset, src + srcOffset, numBytes);
	 */

    private native static void copyJni(int[] src, int srcOffset, Buffer dst, int dstOffset, int numBytes); /*
		memcpy(dst + dstOffset, src + srcOffset, numBytes);
	*/

    private native static void copyJni(long[] src, int srcOffset, Buffer dst, int dstOffset, int numBytes); /*
		memcpy(dst + dstOffset, src + srcOffset, numBytes);
	*/

    private native static void copyJni(float[] src, int srcOffset, Buffer dst, int dstOffset, int numBytes); /*
		memcpy(dst + dstOffset, src + srcOffset, numBytes);
	*/

    private native static void copyJni(double[] src, int srcOffset, Buffer dst, int dstOffset, int numBytes); /*
		memcpy(dst + dstOffset, src + srcOffset, numBytes);
	*/

    private native static void copyJni(Buffer src, int srcOffset, Buffer dst, int dstOffset, int numBytes); /*
		memcpy(dst + dstOffset, src + srcOffset, numBytes);
	*/
}
